Yesterday we disassembled the inlet line (just before the turbo) from a Lancer EVO VI in stock form. As usual, the boost gauge always showed us 16psi (peak) but we noticed that compressor blades had been making contact against compressor housing and there were oil traces along all the inlet lines (before and mostly after the turbocharger: intercooler, blow off, etc).

Performace had not changed(?) but our friend told us that lately he had been hearing a noise (from turbo) every time engine reached 2200rpm and then dissapeared...

It seems that a boost gauge is not enough so what else do we need to check turbo is working properly?...by the other hand, oil in inlet line could generate a serious problem to the engine.

 

I would
1) take apart the intake line. Before & after the turbo, look for heavy amounts of oil. A thin layer of oil is nothing to worry about. Your PCV puts that in. Get a catch can if it bothers you.

2) feel the impeler shaft for "play"

Dont yank it, dont push it. Just a VERY gentel wiggle with your finger tips. It shouldnt move more then 1/48th of an inch (example) I dont know the exact clearance specs.

3) bring the marks on the turbo housing to Mitsu's attention.

A 16G should last ALONG time.

 

The most obvious indication of a turbo death is the dreaded turbo whine, it gives my skin chills, check it out Turbo death, not for the faint of heart

 

Thanx for the info guys.
I think all this is a result of bronze bearings wear and that´s why the compressor blades reached housing.
This is a 2nd hand EVO VI and it was in really stock form: no turbotimer, no boost pressure gauge, no MBC, nothing. It has around 60000km then i think the former owner used it as an "every day" car.

With regard to the death turbo sound, i wonder how much of boost pressure that turbo was generating. Despite of the fact that sound seemed to be very similar (but only when passing through 2200rpm), we allways read 16psi in boost gauge.

 

the best way to check is a turbine RPM gauge and compare it with the factory turbo or just unbolt it and check the turbine blades

 

yeah, we are going to install a new turbo and definitly verify what happened with the failed one.
First of all we checked compressor blades and they were making contact against housing, that was our first indication with regard to what could be generating that sound but we still need to check turbine blades...

 

Considering that the impellor blades are hitting the housing, it sounds like worn turbo bearings to me.

SC~

 

I agree with you.
There is another option instead of changing the former turbo with a new one: change compressor wheel, get the shaft dynamically balanced and place ball bearings instead of bronze ones.
Let´s see what will happen...perhaps we could save many dollars.

 

burning oil?

 

That sound is definately a bad sign! LOL! There are a couple of ways to tell before that. You could be burning oil under boost. Indicating that some of the seals are worn. If the compressor wheel is making contact then you are a lucky man. I budy of mine shredded his comp. wheel but it got stuck in the intercooler. I knew because I wouldn't build any boost. It freaked me out because i just flew by a bunch of people on the highway and when i tried to accelerate again.....nothing. I poked around under the hood and heard that awful noise when i revved the engine.
You could get a new compressor wheel and have it rebuilt, but make sure the inner part of the compressor housing is in god shape. When my turbo took a dump I got a bigger one!

 

Bringing this from the dead cuz i dnt feel like adding another thread..

Anyways.. when i spool up is seem fine.. normal turbo sound but when I go past say 4k RPM it sounds like my turbo is drilling something.. is whistling and stuff.. and it only does it at high boost..